JP4258232B2 - Optical information reader - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical information reading apparatus that reads an information code such as a barcode.
[0002]
[Prior art]
This type of conventional optical information reader (barcode reader) includes an illumination optical system including a plurality of LEDs and an illumination lens disposed in front of the LED, an imaging lens, and a light receiving sensor. And a light receiving optical system provided. A reading object such as paper (label) on which a barcode is printed is irradiated with horizontally long illumination light through the reading opening at the front end of the case by the illumination optical system, and reflected light from the reading object is received by the light receiving optical system. Based on the received light, the barcode is read.
[0003]
In this case, conventionally, as the illumination lens, it has been common to use a kamaboko type lens having an emission surface portion of a cylindrical surface (cylindrical surface). On the other hand, in an appearance inspection apparatus provided with a line sensor, it has been considered to make the illumination light uniform by adopting a lenticular lens as the illumination lens (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-55060
[Problems to be solved by the invention]
As shown in FIG. 10 , the lenticular lens 1 described above has, for example, a shape having a number of convex lens strips 1a continuously on the exit surface side, thereby allowing incident light from the LED 2 to be laterally (reading width direction). The light is diffused and emitted. However, the lenticular lens 1 has an inflection point 1b between the convex lens strips 1a. Since the emitted light is not emitted at the inflection point 1b, the amount of light is wasted and the illumination light is sufficient. There is a disadvantage that it is not uniform.
[0006]
Furthermore, in the above-described appearance inspection apparatus of Patent Document 1, since the distance between the illumination optical system and the object is constant, there is no need to consider the deviation between the illumination optical axis and the imaging optical axis. However, in a barcode reader where the distance between the illumination optical system and the object to be read fluctuates, the illumination light is appropriately applied to the reading position (without shifting in the vertical direction) in the entire reading depth range. For this purpose, it is necessary to minimize the deviation between the illumination optical axis and the imaging optical axis (to eliminate the deviation).
[0007]
The present invention has been made in view of the above circumstances, and an object thereof is to obtain uniform and bright illumination light, and always to be read even if the distance between the read target and the illumination optical system varies. It is an object of the present invention to provide an optical information reader capable of irradiating illumination light at an appropriate position.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, an optical information reader according to the present invention is a multi-row lens in which an illumination lens of an illumination optical system is formed by alternately arranging a plurality of concave lens rows and convex lens rows in a reading width direction. And a rod-shaped lens that condenses the illumination light in a direction perpendicular to the reading width. (Features of the Invention of Claim 1)
[0009]
According to this, the light from the illumination light source can be uniformly diffused in the reading width direction by the multi-row lens of the illumination lens, and the illumination light that is not diffused in the direction perpendicular to the reading width by the rod-like lens is obtained. Can do. At this time, since the multi-row lens has a plurality of concave lens rows and convex lens rows alternately and continuously, all the light from the illumination light source can be passed, and efficient and bright illumination light can be obtained. it can. In addition, since the illumination lens is configured by integrally including a multi-row lens and a rod-shaped lens, the configuration can be simplified as compared with the case where the illumination lens is provided separately. Weight reduction can be achieved.
[0010]
At this time, the multi-row lens can be formed such that a plurality of concave lens strips and convex lens strips are alternately and smoothly continuous, and the curvature radii of the concave lens strips and the convex lens strips can be all constant. Item 2). Further, if the optical axis of the illumination light is arranged in the same plane as the optical axis of the light receiving optical system (the invention of claim 3 ), it relates to the distance between the reading object and the illumination optical system. Therefore, it is possible to always irradiate an appropriate reading position with illumination light.
[0011]
By the way, in this type of optical information reader, there is a tendency that the peripheral portion in the reading width direction is received darker than the central portion due to the characteristics of the light receiving optical system (imaging lens). Therefore, the illumination lens is configured to have different optical characteristics between the peripheral portion in the reading width direction and the central portion so that the light diffusion range is narrower in the peripheral portion than in the central portion. (Invention of claim 4 ) According to this, it is possible to compensate for the darkening of the peripheral portion due to the characteristics of the light receiving optical system by increasing the concentration of the illumination light in the peripheral portion, and the readability can be improved.
[0012]
More specifically, by a curved surface in front Symbol widthwise reading a rod lens, it is possible to further narrow the diffusion range of light than the peripheral portion toward the center portion (the invention of claim 5). Relatively simple configuration, it is possible to change the optical characteristics and the peripheral portion and the central side portion.
[0013]
In order to indicate the reading position, a guide light optical system including a guide light source that emits laser light and a guide lens that spreads light emitted from the guide light source in the reading width direction is also provided. In the case of having a simple guide light optical system, the guide lens can be formed integrally with the illumination lens described above (invention of claim 6). Thereby, simplification of a structure can be achieved.
[0014]
Furthermore, when the above-described illumination optical system is arranged symmetrically with respect to the light receiving optical system, the illumination lenses of the left and right illumination optical systems are integrally connected by a connecting portion that does not function as a lens. It can be provided in a form (invention of claim 7). According to this, the left and right illumination lenses can be integrated, and the number of parts can be reduced and the assemblability can be improved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, with the first embodiment of the present invention will be described with reference to FIGS. Here, a specific example is given of the case where the present invention is applied to a hand-held (handy type) barcode reader as an optical information reader.
[0016]
As shown in part of FIG. 7, the barcode reader 11 as an optical information reading device according to the present embodiment has a vertically long case 112 with a size that can be operated with one hand. As shown in FIG. 1, an illumination optical system 13 as an illuminating means, a light receiving optical system 14 as a light receiving means, and guide light irradiation for reading a barcode recorded on a reading object L such as a label (not shown). A guide light optical system 15 as means is provided. The front end surface of the case 12 is provided with a reading window (reading port) 12a having a horizontally long rectangular shape and having translucency.
[0017]
As shown in FIG. 7, a display unit 16 and a key operation unit 17 are provided on the upper surface of the case 12. Although not shown, for example, a two-stage pressing operation can be performed on the side surface of the case 12. Trigger switch is provided. Further, although not shown in the figure, the case 12 includes a control circuit for performing overall control and decoding processing of the read barcode, a communication circuit for performing communication with the outside, and a secondary serving as a drive power source. A battery or the like is provided.
[0018]
Here, the optical systems 13, 14, 15 will be described. First, as shown in FIG. 1, the light receiving optical system 14 is disposed in front of the light receiving sensor 18 including a light receiving sensor 18 formed of a CCD area sensor, for example, which is disposed horizontally in the center of the case 12. An imaging lens 19 is provided. In this case, the reading optical axis O of the imaging lens 19 extends so that the center of the reading window 12a is orthogonal to the surface of the reading window 12a. The field of view (reading range) F1 (the outer edge is indicated by a thin line) of the light receiving optical system 14 is set slightly smaller than the size of the reading window 12a. Although not shown and described in detail, the imaging lens 19 is configured by arranging a plurality of lenses in a lens barrel.
[0019]
The illumination optical system 13 is disposed symmetrically on the left and right sides of the imaging lens 19, and is disposed on the front side of a plurality of (two in FIG. 1) LEDs 20 as illumination light sources. And an illumination lens 21 having a horizontally long shape. In the present embodiment, the left and right illumination lenses 21 and 21 are provided as a lens coupling body 22 that is integrally coupled by a coupling portion 22a that does not function as a lens located in the central portion. Further, the lens coupling body 22 is configured by integrally including guide lens portions 23 and 23 at both left and right end portions. Details of the shape of the illumination lens 21 will be described later.
[0020]
Thus, in the illumination optical system 13, the light emitted from the LED 20 is condensed and diffused by the illumination lens 21 and spreads in the horizontal direction (reading width direction), and as a strip-shaped illumination light in the vertical direction. Thus, the illumination light is irradiated from the reading window 12a toward the front (reading object L). At this time, the illumination optical axis of the illumination light emitted from the left and right illumination lenses 21 is positioned in the same optical plane as the optical plane including the reading optical axis O of the imaging lens 19 and the light receiving sensor 18. It has become so. Further, the irradiation range in the lateral direction of the illumination light is slightly wider than the visual field F1 of the light receiving optical system 14 as shown by a thin line F2 in FIG.
[0021]
In addition, the guide light optical system 15 is provided with a pair positioned on the left and right outer sides of the illumination optical system 13, and as shown in FIG. 6, for example, a guide composed of a semiconductor laser or the like that emits red laser light. The light source 24 and a guide lens arranged in front of the light source 24 are configured. In this case, the guide lens is provided at the outer end of the lens coupling body 22 (illumination lens 21). 23 is provided in an integrally added form.
[0022]
The guide lens unit 23 functions to diffuse the laser light from the guide light source 24 in the horizontal direction (see FIG. 1) and to focus the light in the vertical direction (see FIG. 6) and output it as guide light. It has become. At this time, with respect to the vertical direction, the focus is set near the reading reference distance. Further, the lateral irradiation range of the guide light is slightly wider than the visual field F1 of the light receiving optical system 14 and the illumination light irradiation range F2, as indicated by a thin line F3 in FIGS. Thus, the guide light optical system 15 emits horizontally long guide light from the reading window 12a toward the front (reading object L).
[0023]
With the above configuration, the trigger is made when the user turns the reading window 12a of the case 12 so as to be substantially parallel to the reading object L on which the horizontally long barcode is recorded and close to the reading reference distance. When the switch is turned on at the first stage (so-called half-press), the guide light optical system 15 irradiates the reading object L with a horizontally long strip-shaped guide light (red light) through the reading window 11a.
[0024]
Therefore, the user aligns the case 12 so that the guide light crosses, for example, the center of the barcode, and turns on the trigger switch in the second stage. Then, after the guide light is turned off, this time, the illumination optical system 13 irradiates the barcode with the horizontally long strip-shaped illumination light through the reading window 12a, and the reflected light from the barcode enters through the reading window 12a and is connected. An image is formed on the light receiving sensor 18 through the image lens 19 so that the bar code is read.
[0025]
Now, the illumination lens 21 will be described in detail with reference to FIGS. The illumination lens 21 is formed, for example, from a synthetic resin into a horizontally long rod shape, and a multi-row lens in which a plurality of concave lens strips and convex lens strips are alternately arranged in the reading width direction, and a reading width of illumination light. And a rod-shaped lens that condenses light in a direction perpendicular to each other.
[0026]
Specifically, as shown in FIGS. 2 and 3, the incident surface portion (surface on the LED 20 side) of the illumination lens 21 has a plurality of convex lens strips 25a and concave lens strips 25b extending in the vertical direction alternately in the horizontal direction. The multi-lens lens surface 25 is formed. At this time, the convex lens strips 25a and the concave lens strips 25b are both curved in a circular arc shape and formed so as to be continuous in a smooth state. In this case, the curvature radii R of the convex lens strip 25a and the concave lens strip 25b are all equal.
[0027]
On the other hand, as shown in FIG. 4, the exit surface portion of the illumination lens 21 is a rod-shaped lens surface 26 having a gentle cylindrical surface with the horizontal direction as an axis. At this time, as shown in FIG. 3 and FIG. 5, in this embodiment, the rod-shaped lens surface 26 is formed with a constant lens thickness at the central portion (inner side) in the reading width direction (lateral direction). On the peripheral portion (outer portion) side, the curved surface portion 26a (concave surface as viewed from above) is formed so that the thickness of the lens gradually increases when viewed from above. The optical characteristics are different.
[0028]
Next, the operation of the above configuration will be described. In the illumination optical system 13 configured as described above, the light from the LED 20 is incident on the multiple lens surface 25 of the illumination lens 21 and diffused in the lateral direction, and is condensed in the vertical direction by the rod-shaped lens surface 26. As a whole, it is emitted as illumination light having a uniform horizontally long band shape. At this time, the multi-lens lens surface 25 has a plurality of convex lens strips 25a and concave lens strips 25b alternately and continuously in a smooth state, so that the lens surface like the conventional lenticular lens 1 is bent, All the light from the LED 20 can be transmitted, and efficient and bright illumination light can be obtained without waste.
[0029]
In this type of barcode reader 11, the distance between the reading window 12 a (illumination optical system 13) of the case 12 and the reading object L varies, but the optical axis of the illumination light is received. Since the optical axis O of the optical system 14 is optically arranged in the same plane, the illumination light is not shifted in the vertical direction in the entire reading depth regardless of the distance between the reading object L and the illumination optical system 13. The illumination light can always be irradiated to an appropriate reading position.
[0030]
By the way, in the above configuration, due to the characteristics of the imaging lens 19 in the light receiving optical system 14, when reading a barcode, the peripheral portion in the reading width direction tends to be received so as to be darker than the central portion. is there. However, in this embodiment, by providing the curved surface portion 26a on the peripheral side of the rod-shaped lens surface 26 of the illumination lens 21, as shown in FIG. The light diffusion range b of the portion becomes narrower, and as shown in FIG. 5, the concentration of the illumination light becomes stronger on the peripheral side of the barcode. As a result, it is possible to compensate for the darkening of the peripheral portion due to the characteristics of the light receiving optical system 14, and to improve the readability.
[0031]
Further, the illumination lens 21 is configured by integrally including the multi-lens lens surface 25 and the rod-shaped lens surface 26, so that the configuration is simpler than the case where the illumination lens 21 is provided separately (consisting of two lenses). Thus, the entire device can be reduced in size and weight. Furthermore, the left and right illumination lenses 21 are configured as a lens coupling body 22 that is integrally coupled by a coupling portion 22 a that does not function as a lens, and the guide lens unit 23 that constitutes the guide light optical system 15 is also configured. Since the lens coupling body 22 is integrated, the configuration can be further simplified, and the number of parts can be reduced and the assembling property can be improved.
[0032]
As described above, according to the present embodiment, the illumination lens 21 of the illumination optical system 13 is configured by integrally including the multiple lens surface 25 and the rod-shaped lens surface 26, and the optical axis of the illumination light is received. Since the optical system 13 is arranged optically in the same plane as the optical axis O, uniform and bright illumination light can be obtained, and the distance between the reading object L and the illumination optical system 13 varies. Even in this case, there is an excellent effect that illumination light can always be applied to an appropriate position of the reading object L.
[0035]
FIG. 8 shows a second embodiment of the present invention . In this embodiment, the guide light optical system 40 includes a guide light light source 24 and an illumination lens (on the illumination optical system) located in front of the guide light light source 24. (Not shown) and a separate guide lens 41 . The guide light optical system may be provided as necessary.
[0036]
In the above-described first embodiment, although as a rod lens surface 26 of the illumination lens 21 is provided a curved portion 26a, as in the illumination lens 51 according to the third embodiment shown in FIG. 9, the multi Even if all the curvature radii R of the strip lens surface 52 are made constant, and the rod-shaped lens surface 53 is configured to have a uniform shape in the lateral direction, the intended purpose can be achieved .
[0037]
Although not shown, a diaphragm plate that squeezes the light from the LED in the vertical direction may be provided between the illumination light source (LED) and the illumination lens to obtain illumination light with higher contrast. Can do. In the above embodiment, the optical axis of the illumination light and the optical axis O of the light receiving optical system are physically positioned in the same plane. However, even when the optical path is bent by a mirror, for example. If the optical axis of the illumination light immediately before irradiating the reading object L and the optical axis immediately after reflection of the reflected light reflected from the reading object L and imaged by the imaging lens are in the same plane, the optical It can be said that they are in the same plane.
[0038]
Furthermore, in the first embodiment, the left and right illumination lenses are integrally connected by the connecting portion. However, separate illumination lenses may be provided on the left and right, respectively. In addition, the present invention can be applied not only to handy (handheld) type bar code readers but also to fixed type optical information readers. Also, the configuration of the light receiving optical system and the guide light optical system, the case The shape and the like can be appropriately changed and implemented without departing from the gist, such as various modifications.
[Brief description of the drawings]
FIG. 1 shows a first embodiment of the present invention, and is a cross-sectional plan view and a longitudinal side view showing the configuration of an optical system of a barcode reader. FIG. 2 enlarges the shape of a multi-row lens surface of an illumination lens. Fig. 3 is a plan view showing the configuration of the illumination optical system. Fig. 4 is a vertical side view showing the configuration of the illumination optical system. Fig. 5 shows the relationship between the shape of the rod-shaped lens surface and the intensity of the irradiation light. FIG. 6 is a side view showing a configuration of a guide light optical system. FIG. 7 is a plan view showing a reading range of a bar code reader and an instruction range of guide light. FIG. 8 shows a second embodiment of the present invention. FIG . 9 is a view showing the shape of an illumination lens according to a third embodiment of the present invention . FIG. 10 is a view corresponding to FIG. 2 showing a conventional example.
In the drawings, 11 is a barcode reader (optical information reader), 12 is a case, 12a is a reading window, 13 is an illumination optical system, 14 is a light receiving optical system, 15 and 40 are guide light optical systems, and 18 is a light receiving sensor. , 19 is an imaging lens, 20 is an LED (illumination light source), 21 and 51 are illumination lenses, 22 is a lens coupling body, 22a is a coupling portion, 23 is a guide lens portion, 24 is a guide light source, and 25 and 52. Is a multi-lens lens surface, 25a is a convex lens strip, 25b is a concave lens strip, 26 and 53 are rod-shaped lens surfaces, 26a is a curved surface portion, and 41 is a guide lens.

Claims (7)

An illumination optical system that includes an illumination light source composed of LEDs and an illumination lens that collects and / or diffuses incident light from the illumination light source and emits illumination light that is long in the reading width direction toward the reading object; A light receiving optical system including a light receiving sensor for receiving reflected light from a reading object,
The illumination lens includes a multi-row lens in which a plurality of concave lens strips and convex lens strips are alternately and continuously arranged in the reading width direction, and a rod-shaped lens that condenses the illumination light in a direction perpendicular to the reading width. And an optical information reading device. 2. The multi-row lens is formed such that a plurality of concave lens strips and convex lens strips are alternately and smoothly continuous, and the curvature radii of the concave lens strip and the convex lens strip are all constant. The optical information reading device described. 3. The optical information reader according to claim 1 , wherein an optical axis of the illumination light is disposed in the same optical plane as an optical axis of the light receiving optical system . The illumination lens has a different optical characteristic between a peripheral portion in the reading width direction and a central portion, and the peripheral portion is configured to make the light diffusion range narrower than that in the central portion. An optical information reading apparatus according to any one of claims 1 to 3 . Said illumination lens, by said curved surface to rod-lens reading width direction, the optical information reading apparatus according to claim 4, wherein the optical properties has been configured differently. A guide light optical system including a guide light source that emits laser light and a guide lens that expands light emitted by the guide light source in the reading width direction;
6. The optical information reading apparatus according to claim 1, wherein the guide lens is formed integrally with the illumination lens.   The illumination optical system is arranged symmetrically with respect to the light receiving optical system, and the left and right illumination lenses are provided in a form integrally connected by a connecting portion that does not function as a lens. An optical information reading apparatus according to any one of claims 1 to 6.

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